Down servers slowing us down?

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Yesterday we were having a rough go with our internet mail.  Checking the
4 mail#.box files on our INTERNOTES partition I noticed several stacked
up.  I cleared out the old, and stopped stuff.  There were several bound
for ligtel.com - a local internet provider.  Evidently they were down
yesterday.  I moved them all out to a copy of the mail.box, (robmail.rob).
 Then I stopped/started the router.  Then I started moving them back in
chunks.  When I got to the ligtel.com, and a few others, the number of
emails in the mail#.box files started growing.  Therefore I moved the
ligtel.com, and a few others, back to the temporary copy.  Today I moved
them back and, evidently ligtel.com is back up because the mail went right
out.

Issue #1)  How do we get a downed domain to stop bringing all of our email
to a screeching halt?  Sounds like a potential dns attack hole.

Issue #2)  When I move the email back and forth it kept changing the
sender of the email to the name of the Notes user I did it under.  (I
quickly changed to a another address.  If it was going to a nondesirable
site I didn't want the replies to farm my address.)  This played havoc
with replies, and with determining who sent the mail in the first place.

Rob Berendt
--
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
Benjamin Franklin